Instant communication services, popularized by NEXTEL® DIRECT CONNECT® and often referred to as “push to talk,” allow a caller to select one or more callees to receive a real-time or near-real-time message from the caller. The message typically comprises a voice signal, such as speech. Instant communication technology has been widely deployed in public safety markets as well as for businesses with distributed, mobile workforces. Public safety markets are exemplified by police, firefighting, and national security services. Distributed, mobile workforces are exemplified by home repair technicians, delivery services, and transportation services, such as taxi or limousine fleets.
Traditional instant communication services are based on circuit-switched technology and facilitate instant communication sessions between one or more mobile devices such as cell phones. A performance metric of these services is the speed at which instant communication sessions can be established. Users of these services expect an experience as rapid as that of a walkie-talkie, and may become frustrated with the instant communication service if it takes longer than a few seconds to establish an instant communication session. Circuit-switched technology can provide a low-latency instant communication service because end-to-end communications circuits can be reserved across the network for the signaling and bearer traffic associated with the service.
As mobile and cellular voice services are migrated to packet-switched networks, instant communication services may be implemented using packet-switching protocols, such as the Internet Protocol (IP). However, IP was initially a best-effort protocol, and in practice it did not provide low-latency service. For example, traditional IP did not allow prioritization of some types of sessions (such as instant communication sessions) over other types of sessions (such as web browsing sessions).
Furthermore, packet-switched wireless data infrastructure components are designed for maximizing session throughput rather than minimizing session establishment latency. Thus, these traditional components are poorly equipped to provide low-latency instant communication services using IP.
Additionally, some wireless technologies release all air interface traffic channels used by a wireless communication device if the wireless communication device does not use these channels for a given period of time (usually 10-30 seconds). A wireless communication device without any allocated traffic channels is considered to be dormant, and several seconds may be needed to “wake up” such a dormant wireless communication device. Thus, dormancy adds even more potential delay to instant communication session establishment latency.
Accordingly, it is desirable to develop new methods and systems that facilitate rapid establishment of instant communication sessions over wireless, IP-based networks.